/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: fzykd
 * Date: 2022-04-22
 * Time: 8:49
 */
class ListNode{
    public int val;
    public ListNode next;

    public ListNode(int val){
        this.val = val;
    }
}
public class MyListNode { //链表
    public ListNode head;
    //遍历链表
    public void display(){
        ListNode cur = this.head;
        while (cur != null){
            System.out.print(cur.val+" ");
            cur = cur.next;
        }
        System.out.println();
    }


    //头插法
    public void addFirst(int data){
        ListNode node = new ListNode(data);
        node.next = this.head;
        this.head = node;
    }
    //尾插法
    public void addLast(int data){
        ListNode node = new ListNode(data);
        ListNode cur = this.head;
        if (this.head == null){
            this.head = node;
            return;
        }
        while (cur.next!= null){ // 循环条件和遍历的不一样
            cur = cur.next;
        }
        cur.next = node;
    }
    //任意位置插入,第一个数据节点为0号下标
    public void addIndex(int index,int data){
        ListNode node = new ListNode(data);
        if (index < 0 || index > this.size()){
            System.out.println("index:"+index+"这个位置不合法！");
            return;
        }
        if (index == 0){
            addFirst(data);
            return;
        }
        if (index == size()){
            addLast(data);
            return;
        }
        ListNode prev = this.head; // 找到插入位置的前驱
        while (index-1 > 0){
            prev = prev.next;
            index--;
        }
        node.next = prev.next;
        prev.next = node;

    }
    //查找是否包含关键字key是否在单链表当中
    public boolean contains(int key){
        ListNode cur = this.head;
        while (cur != null){
            if (cur.val == key){
                return true;
            }
            cur = cur.next;
        }
        return false;
    }

    /**
     * 找到删除节点的前驱节点
     * @param
     */

    public ListNode prevNode(int key){
        ListNode prev = this.head;
        while (prev != null){
            if (prev.next.val == key){
                return prev;
            }
            prev = prev.next;
        }
        return null;
    }

    //删除第一次出现关键字为key的节点
    public void remove(int key){
        ListNode cur = this.head;
        ListNode prev = prevNode(key);
        while (cur != null){
            if (cur.val == key){
                prev.next = cur.next;
                break;
            }
            cur = cur.next;
        }
    }
    //删除所有值为key的节点
    public void removeAllKey(int key){
        ListNode cur = this.head;
        ListNode prev = prevNode(key);
        while (cur != null){
            if (cur.val == key){
                prev.next = cur.next;
                break;
            }
            cur = cur.next;
        }
    }
    //得到单链表的长度
    public int size(){
        int count = 0;
        ListNode cur = this.head;
        while (cur != null){
            count++;
            cur = cur.next;
        }
        return count;
    }
    public void clear(){};
}
